Dominance of legume trees alters nutrient relation

Authors: Ilyas Siddique Vera Lex Engel John A Parrotta David Lamb Gabriela B Nardoto Jean P H B Ometto Luiz A Martinelli Susanne Schmidt

Publish Date: 2008/03/19

Volume: 88, Issue: 1, Pages: 89-101

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Abstract

Failures in reforestation are often attributed to nutrient limitation for tree growth We compared tree performance and nitrogen and phosphorus relations in adjacent mixedspecies plantings of contrasting composition established for forest restoration on Ultisol soil originally covered by tropical semideciduous Atlantic Forest in Southeast Brazil Nutrient relations of four tree species occurring in both planting mixtures were compared between a legumedominated speciespoor direct seeding mixture of earlysuccessional species “legume mixture” and a speciesdiverse legumepoor mixture of all successional groups “diverse mixture” After 7 years the legume mixture had 6fold higher abundance of N2fixing trees 177 higher total tree basal area 22 lower litter C/N sixfold higher in situ soil resinnitrate and 40 lower in situ soil resinP compared to the diverse mixture In the legume mixture nonN2fixing legume Schizolobium parahyba FabaceaeCaesalpinioideae had significantly lower proportional N resorption and both naturally regenerating nonlegume trees had significantly higher leaf N concentrations and higher proportional P resorption than in the diverse mixture This demonstrate forms of plastic adjustment in all three nonN2fixing species to diverged nutrient relations between mixtures By contrast leaf nutrient relations in N2fixing Enterolobium contortisiliquum FabaceaeMimosoideae did not respond to planting mixtures Rapid N accumulation in the legume mixture caused excess soil nitrification over nitrate immobilization and tighter P recycling compared with the diverse mixture The legume mixture succeeded in accelerating tree growth and canopy closure but may imply periods of N losses and possibly P limitation Incorporation of species with efficient nitrate uptake and P mobilization from resistant soil pools offers potential to optimize these tradeoffsWe thank collaborators at UNESP–FCA for their help with sampling and lab analyses Aparecido A de Arruda Beatriz RM Caes José C Coelho Dr Hélio Grassi Filho Dr Iraê A Guerrini Andreza M Martins Paulo E dos S Massoca Elder C de Mattos Ana Maria M Rufino Manoel C Santana We thank Dr MZ Moreira for technical support CENA–USP and two anonymous reviewers for helpful comments IS was supported by an International Postgraduate Research Scholarship from The University of Queensland The sampling and analyses were funded by The University of Queensland and the reforestation experiment was established with funding from the USDA Forest Service International Institute of Tropical Forestry

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